If you have tried all of the above and it still doesn't work. You "could" try opening it up and seeing if the display (daughter board) ribbon cable worked itself loose and may need reseating. Just an idea prior to seeing about taking it in for service.

I owned a Bass Pod (non-XT), where after about 2 years I couldn't edit ANYTHING, only could go through factory presets. Took it to an authorized repair shop & they said it would cost roughly $120US, & didn't guarantee it would fix the problem. I bought a new Bass PodXT instead, no problems after several years & more, better sounds overall.